Bread won't rise!

What happened to the sourdough starter? Were you feeding it? Still, it seems odd for it to die after 2 days. Hmm. Not sure how you test if the flour is OK. How about trying to activate the yeast with the flour - some water, some flour, some yeast, leave for 10-15 minutes and see what happens?

Thanks for your responses. I'm wondering now if it might be the flour because I have made the Paul Hollywood sourdough starter, the one with the grapes and that was great for the first two days, but has now died

Even with fast acting yeast, I activate first in water - because I do not want to have kneaded dough only to find out the yeast won't work! I do this as a hangover from when I didn't bake very often and used out of date yeast regularly. So, measure out slightly less than the water/liquid used in the recipe, use tepid water as this activates the yeast faster, then add your yeast and a pinch of sugar. You should get bubbles and a beigey gloop on top of the water in a few minutes. Add this to your flour.

If your yeast is alive when you put it in, then something has killed it afterwards Most likely is the salt - either mix the salt through the flour before adding yeast, or add them to either side of the bowl. Alternatively, you cooked the yeast by leaving it to rise somewhere too hot/too cold.

Tried making bread this morning following Paul Hollywood's recipe, with dried yeast. He said leave for an hour or so and it will have doubled in size. Eight hours later - absolutely nothing! It's in the kitchen and I've been in here all day cooking and ironing.